Displays having lenticular screens have become one of several different types of stereoscopic devices that are being developed and considered for three dimensional (3D) displays. Typical 3D displays with lenticular screens work well as long as viewers are positioned within certain viewing angles, viewing distances, and viewing orientations with respect to the lenticular screen. The reason is a lenticular screen is a collection of optical lenses that takes advantage of the phenomenon of parallax. In other words, lenticular components guide light from each stripe to each eye correctly for a 3D effect, and therefore each eye has an independent and different picture view. Optimal distance and optimal viewing angle each depend on the lenticular optical properties such as focal length.
FIG. 5 is a cross sectional view of a conventional lenticular screen 18 where the lenticular lenses 21 run in vertical columns and each vertical column includes a series of left pixels 16 designed to be seen by left eyes 19 and each vertical column includes a series of right pixels 17 designed to be seen by right eyes 20. In the figure, the viewing distance is optimized by the lenticular component's optical properties (e.g. focal length) such that the left eye 19 only sees the left pixels 16 and the right eye 20 only sees the right pixels 17. However, as the viewer moves from the optimized position, a blending of the left and right pixels will begin to occur, thereby diminishing the 3D effect. This is called “cross talk.”
The lenticular screen 18 has been further improved by constructing the lenticular lenses with liquid crystal material which can change the refractive index of the lenses when the liquid crystal material is poled. Such capability also allows for easy switching between two dimensional (2D) and three dimensional (3D) viewing. However, the position of the viewer is still critical for these lenticular screens with liquid crystal material.
Another 3D display concept is the parallax display. With this technology, the screen includes a parallax barrier instead of lenticular components in front of the left and right images. FIGS. 6A and 6B generally represent a conventional parallax display yielding a vertically interlaced image 11. FIG. 6A shows that the left pixel columns 12 effectively yield the left image 14 and the right pixel columns 13 yield the right image 15. The viewers who are appropriately positioned with respect to the display will see the left pixel columns 12 with their left eye 19 and see the right pixel columns 13 with their right eye 20. FIG. 6B shows how the parallax barrier 28 generally permits the left eye 19 and the right eye 20 to see the left pixels columns 12 and the right pixel columns 13, respectively. As with the conventional lenticular displays, if not appropriately positioned, the viewer will see both the left and right columns with both eyes because light delivery is angle sensitive for a certain separation between two eyes.
There are also other display technologies for 3D viewing. One is the use of passive glasses with polarized light projection. Another is the use active auto-shutter glasses using LCDs. However, it is hard to judge which is better because requirements vary for different applications (e.g., passive methodology is more favored for cinema viewing due to multi-viewing positions and active methodology is typically favored for gaming).
With the current state of the art in 3D lenticular screen and parallax screen technologies having restrictive viewer positional constraints and the other 3D technologies requiring glasses, a need exists for a novel screen that can broaden the viewing latitude without requiring glasses.